The present invention relates to a refill mechanism for filling toner powder from a refill container into a toner reservoir of a copier or printer, which includes
a refill opening formed in the top of the toner reservoir;
a drawer slideable between an open position and a closed position for opening and closing the refill opening;
a spout formed on the refill container and closed by a slide; and
a mounting structure for mounting the spout on the toner reservoir in a position above the refill opening, such that the slide is engaged in a recess of the drawer and, when the drawer is moved into an open position, is moved together with the drawer for opening the spout, so that the toner powder drops into the toner reservoir.
A copier, a printer or any other device which develops an image with toner powder utilizes a toner reservoir which accommodates a supply of fine toner powder which is gradually consumed in the course of image development. From time to time, the toner reservoir needs to be refilled with toner powder from a refill container, e.g. a bottle, a refill cartridge or the like. Since the toner powder typically consists of very fine toner particles, even a slight air draft is sufficient for swirling up a dust of toner particles, when the toner powder is exposed to the open air. Since the toner is strongly pigmented, this dust is likely to stain the environment. For this reason, it is necessary that the refill mechanism is designed to prevent the toner powder from being exposed to the open air even during the refill process, so that no toner dust will be generated and the user who refills the toner reservoir is protected against direct contact exposure to the toner powder.
When the drawer is opened, the lower surface of the spout wipes over the top surface of the drawer, and the toner powder is swept into the refill opening. It turns out, however, that in the course of frequent refill processes occurring during the lifetime of the copier, a certain amount of toner powder may accumulate on the top surface of the drawer. As a result, slight amounts of toner powder may escape into the environment and may stain the fingers and clothes of the user. More importantly, when the drawer and the slide which are both in sliding contact with the lower surface of the spout are moved back and forth between open and closed positions, toner powder may be entrained into the gap between the sliding surfaces and, due to frictional heat, will be sintered or baked together to form coating layers on the sliding surfaces. These coating layers are eventually peeled-off, so that flakes of sintered toner material are likely to drop into the toner reservoir and disturb the developing process, whereby the quality of the developed images is impaired.
In order to reduce this effect, resilient sealing pads may be employed which are relatively tightly pressed against the sliding surfaces of the slide and the drawer so as to prevent the toner powder from being deposited on these surfaces. This, however, leads to an increased frictional resistance and may make it difficult to manually operate the drawer and the slide.
It is accordingly an object of the present invention to provide a refill mechanism which is easy to operate and nevertheless avoids the formation of toner flakes which may drop into the toner reservoir.
According to the present invention, this object is achieved by the feature that the top surface of the slide is covered by a foil which projects over the trailing edge of the slide, as view ed in the direction of the opening movement, and overlaps with the adjacent edge of the recess of the drawer.
Since the slide and the drawer are both in sliding engagement with the lower surface of the spout and the slide is further engaged in the recess of the drawer, there exists not only a horizontal gap between the lower surface of the spout and the top surfaces of the slide and the drawer, but also a vertical gap between the slide and the wall of the recess at the trailing edge of the slide. In the prior art arrangement, the vertical gap upwardly opens into the horizontal gap, so that a T-shaped gap configuration is obtained. When the drawer is opened, the open vertical gap moves across the open cross-section of the spout and becomes filled with toner powder. Even when a resilient sealing pad is provided at the lower surface of the spout surrounding the opening cross section, so as to wipe off the toner powder from the top surfaces of the slide and the drawer, the toner powder accumulated in the vertical gap cannot be removed. This toner powder is therefore entrained into a region where the horizontal gap exists between the slide and the drawer on the one hand and the sealing pad of the spout on the other hand. Here, the toner powder is supported by the walls of the vertical gap which move relative to the sealing pad, and friction between the toner powder and the sealing paid will cause the toner powder to enter into the horizontal gap and to form sintered flakes.
The present invention is based on the observation that this effect is the main reason for the occurrence of toner flakes. Therefore, according to the present invention, the vertical gap is covered by the projecting part of the foil, so that no toner powder may enter into the vertical gap.
Since the projecting part of the foil overlaps the adjacent edge of the drawer, a minor step is formed between the top surface of the foil and the top surface of the drawer adjacent thereto. When the drawer is opened, the sealing pad of the spout rides over this step, and the toner powder can successfully be wiped off from the surface of the foil and the surface of the drawer in the descending direction of the step. As a result, only minor remnants of toner powder will remain right in front of the step. When the drawer is closed again, the step formed by the foil prevents these remnants of toner from coming into frictional contact with the sealing pad of the spout. Since an increased pressing force exists between the sealing pad and the edge of the foil which forms the step, the toner powder is efficiently prevented from entering into the gap between the top surface of the foil and the sealing pad. In addition, if toner powder adheres to the lower surface of the sealing pad, this toner powder will be scraped off by the edge of the foil which forms the leading edge when the drawer is closed. As a result, the entry of toner powder into the horizontal gap and the formation of toner flakes are successfully prevented.